Abstract: The vertical distribution of organisms in the sediment indicates that animals can be present as deep as 15 cm although at very low abundance at such depths (Fig. 4, Fig. 5 and Fig. 6). Oligochaetes and nematods are the only groups able to deeply penetrate into the sediment at significant densities (Fig. 4) in contrast to all other groups, which stay closer to the sediment surface. Maximal densities however seem to shift to the sediment surface with increasing bathymetric depth, as suggested in Fig. 5 and Fig. 6, so that all animal groups are more concentrated near the surface in the deepest parts of Lake Baikal. In such case, the depth of sediment mixing due to bioturbation appears to decrease with increasing bathymetric depth (Fig. 2b).

Abstract: The vertical distribution of organisms in the sediment indicates that animals can be present as deep as 15 cm although at very low abundance at such depths (Fig. 4, Fig. 5 and Fig. 6). Oligochaetes and nematods are the only groups able to deeply penetrate into the sediment at significant densities (Fig. 4) in contrast to all other groups, which stay closer to the sediment surface. Maximal densities however seem to shift to the sediment surface with increasing bathymetric depth, as suggested in Fig. 5 and Fig. 6, so that all animal groups are more concentrated near the surface in the deepest parts of Lake Baikal. In such case, the depth of sediment mixing due to bioturbation appears to decrease with increasing bathymetric depth (Fig. 2b).

Abstract: The vertical distribution of organisms in the sediment indicates that animals can be present as deep as 15 cm although at very low abundance at such depths (Fig. 4, Fig. 5 and Fig. 6). Oligochaetes and nematods are the only groups able to deeply penetrate into the sediment at significant densities (Fig. 4) in contrast to all other groups, which stay closer to the sediment surface. Maximal densities however seem to shift to the sediment surface with increasing bathymetric depth, as suggested in Fig. 5 and Fig. 6, so that all animal groups are more concentrated near the surface in the deepest parts of Lake Baikal. In such case, the depth of sediment mixing due to bioturbation appears to decrease with increasing bathymetric depth (Fig. 2b).

Abstract: In all abyssal stations, densities are never over an average of c. 3100 individuals m−2 (Fig. 3, Table 1). In contrast, the shallow station (CON01-427, Posolskoe Bank) harbours the highest observed densities (oligochaetes reach densities as high as 13573 individuals m−2 on average). Gammarids are present in this latter station at 128 m deep, while they are absent from all deep stations. The presence of some groups is anecdotal, such as Hydrachnidia (one specimen in a core at 388 m and two specimens in a core at 625 m) and chironomid larvae (two larvae in a core at 625 m). Interestingly, the two deepest Vydrino cores (CON01-105-7, 600 m, and CON01-106-3, 700 m) are virtually free from animals, suggesting that these stations are perhaps the best choice for the study of stratigraphy and climate proxies.